lab experiment number four of Ohm's Law
Answers
Charge: There are two charges in nature i.e., positive and negative. The negative charge is due to electron. Its value is 1.6 x 10-19C. It is measured in coulombs.
Coulomb: One coulomb is the amount of charge present on 6.25 x 1018 electrons.
Electric Current: It is the rate of flow of charge through a conductor. If a net charge Q flows across any cross-section of conductor in time t, then the current I, through the cross-section is
The unit of current is ampere.
One Ampere: One ampere is constituted by the flow of one coulomb of charge per second.
It is measured by a device called ammeter which is always connected in series in a circuit.
Potential difference In an electric circuit carrying current, the work done to move a unit charge from one point to the other is called potential difference.

The SI unit of potential difference is volt (V).
One Volt: When 1 joule of work is done to move a charge of 1 Coulomb from one point to the other then potential difference is of 1 volt.

It is measured by an instrument called the voltmeter. The voltmeter is always connected in parallel in a circuit.
e.m.f.: Electro motive force, is the force which disturbs the equilibrium of free electrons flowing in the metal wire. The source of e.m.f. like cell or battery can develop a potential difference across the ends of the wire and the electrons can flow through the wire.
Ammeter: The number of electrons flowing through a wire can be measured using ammeter. It is always connected in series in the circuit. The positive electrode of battery/cell is connected to the positive electrode of the ammeter and the negative end to the negative electrode of the battery.
Cell: A cell is a device which produces potential difference in the wire and supplies the electrons to flow through the closed circuit. A primary cell produces 1.5 volts of potential difference.
Explanation:
Ohm's law states that the amount of electric current through a conductor in a circuit is directly proportional to the voltage across it. Ohm expressed his discovery in the form of a simple equation, describing how voltage, current, and resistance relate to each other: V=IR. He published his work in 1827.